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VAST-4.4-adcom-extension-type-mismatch

VAST-4.4-adcom-extension-type-mismatch

<Extension> type attribute and AdCOM payload element name disagree

WarningCTV Ad PortfolioIAB CTV Ad Portfolio §Purpose of VAST extAll VAST versions

Short answer

The type attribute names the signal and the child element carries its value. Consumers key off type to decide what to read, so <Extension type="pos"> wrapping a <plcmt> payload will have the wrong value read for the wrong field, or be dropped entirely.

Why this matters in production

This rule is a strong risk signal. Tags with this issue often still parse, but they become brittle across SDKs, SSAI resolvers, and CTV environments. The CTV Ad Portfolio standardises Pause, Screensaver, Overlay, Squeezeback and In-Scene ads, which ran for years on bespoke per-publisher integrations. These rules cover the VAST side of that contract: the NonLinear MediaFiles delivery model, the AdCOM signals round-tripped into Extensions so stitchers can validate the experience without the bid object, and the QR code block. The signaling guidance is final; the VAST 4.4 schema that accompanies it is still a working-group draft, so anything sourced only from the schema is reported as a warning or a note. Affected scope: All VAST versions.

Invalid

<Extension type="pos" ext="adcom">
  <plcmt>5</plcmt>
</Extension>

Valid

<Extension type="plcmt" ext="adcom">
  <plcmt>5</plcmt>
</Extension>
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Other CTV Ad Portfolio rules

VAST-4.4-version-attributeDocument declares VAST 4.4, a working-group draft rather than a published specVAST-4.4-nonlinear-no-renderable-asset<NonLinear> has a SIMID interactive file but no renderable fallback assetVAST-4.4-nonlinear-mediafiles-empty<NonLinear> <MediaFiles> contains no renderable or interactive assetVAST-4.4-nonlinear-simid-iframe<IFrameResource apiFramework="SIMID"> is superseded by <InteractiveCreativeFile> in NonLinearVAST-4.4-nonlinear-video-no-duration<NonLinear> delivers video but has no <Duration>: quartile tracking cannot fireVAST-4.4-adcom-extension-unknown-signal<Extension ext="adcom"> type is not plcmt, pos, playbackmethod or attrVAST-4.4-adcom-signal-not-integerAdCOM signal payload in <Extension> is not an integerVAST-4.4-adcom-plcmt-valueAdCOM plcmt outside the Plcmt Subtypes (Video) range 1–9